Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Configure this policy to allow/disallow ambient authentication for InPrivate and Guest profiles in Microsoft Edge. Ambient Authentication is http authentication with default credentials when explicit credentials aren't provided via NTLM/Kerberos/Negotiate challenge/response schemes. If you set the policy to 'RegularOnly', it allows ambient authentication for Regular sessions only. InPrivate and Guest sessions won't be allowed to ambiently authenticate. If you set the policy to 'InPrivateAndRegular', it allows ambient authentication for InPrivate and Regular sessions. Guest sessions won't be allowed to ambiently authenticate. If you set the policy to 'GuestAndRegular', it allows ambient authentication for Guest and Regular sessions. InPrivate sessions won't be allowed to ambiently authenticate If you set the policy to 'All', it allows ambient authentication for all sessions. Note that ambient authentication is always allowed on regular profiles. In Microsoft Edge version 81 and later, if the policy is left not set, ambient authentication will be enabled in regular sessions only. Policy options mapping: * RegularOnly (0) = Enable ambient authentication in regular sessions only * InPrivateAndRegular (1) = Enable ambient authentication in InPrivate and regular sessions * GuestAndRegular (2) = Enable ambient authentication in guest and regular sessions * All (3) = Enable ambient authentication in regular, InPrivate and guest sessions Use the preceding information when configuring this policy.